Bring a large pot of salted water to a boil and cook the pasta according to package instructions until al dente, about 8-10 minutes. Drain and rinse under cold water.

In a skillet, heat olive oil over medium heat, add shrimp, and sauté until pink and opaque, about 3-4 minutes per side. Set aside to cool.

Chop celery and bell peppers into small, even pieces for mixing.

In a mixing bowl, combine mayonnaise, sour cream, garlic powder, salt, and pepper. Mix until well blended.

In a large bowl, toss together pasta, cooked shrimp, chopped vegetables, and dressing until evenly coated.

Cover the bowl and chill in the refrigerator for at least 30 minutes before serving.